Bushing in Transformer | Types of Bushings | Maintenance of Bushings: Yash Highvoltage
Bushing in Transformer
Transformers are an essential part of the electrical power system, used to step up or step down voltage levels for efficient transmission and distribution of power. One of the critical components of transformers is the bushing, which acts as an insulator between the transformer tank and the external conductors.
A bushing is a hollow cylindrical tube made of high-quality insulating materials such as porcelain, epoxy, or composite materials. It is designed to support the external conductor and provide electrical insulation to prevent leakage of high voltage power. The bushing is connected to the transformer tank through a flange and contains a conductor that extends from the transformer winding to the external circuit.
Bushing serves multiple purposes in a transformer:
Electrical insulation: The primary function of the bushing is to provide electrical insulation between the transformer tank and the external circuit. It prevents the high voltage power from leaking and ensures the safe operation of the transformer.
Support: The bushing supports the external conductors and helps to maintain the alignment between the transformer winding and the external circuit. It also withstands the weight of the conductor and the forces due to wind, vibrations, and other external factors.
Cooling: In some cases, the bushing can be designed to provide cooling for the transformer winding. This is achieved by circulating a cooling fluid through the hollow tube of the bushing, which helps to dissipate the heat generated by the transformer winding.
Types of Bushings:
There are several types of bushings used in transformers, each designed for specific applications and voltage levels:
Oil-Impregnated Paper (OIP) Bushing: OIP bushing is made of paper insulation impregnated with oil. It is used for low and medium voltage transformers.
Resin Impregnated Paper (RIP) Bushing: RIP bushing is made of paper insulation impregnated with epoxy resin. It is used for high voltage transformers.
Gas-Insulated Bushing (GIB): GIB is a gas-insulated bushing that uses SF6 gas as an insulating medium. It is used for high voltage transformers and is preferred for its compact design and high reliability.
Capacitor Bushing: Capacitor bushing uses a capacitor to provide insulation between the transformer winding and the external circuit. It is used for extra-high voltage transformers and provides a low loss and high voltage insulation.
Maintenance of Bushings:
Proper maintenance of bushings is critical for the safe and efficient operation of transformers. Some of the essential maintenance activities include:
Regular inspection of bushings for signs of damage, wear, or leaks.
Monitoring of bushing insulation resistance to detect any changes that may indicate insulation degradation.
Cleaning of bushings to remove any contaminants or debris that may affect the insulation performance.
Replacement of bushings that are damaged or showing signs of wear or degradation.
Conclusion:
Bushing is a critical component of transformers that provides electrical insulation and support to external conductors. Proper selection, installation, and maintenance of bushings are essential for the safe and efficient operation of transformers. With the right care and attention, bushings can provide reliable insulation and support for the life of the transformer.
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